A photoswitchable foldamer system for remote control of thiourea catalysis Katie Foster, Mark P. Walsh and Jonathan P. Clayden* University of Bristol, UK The functioning of biological systems is underpinned by countless molecular communication networks, many of which rely on conformational change to trigger signal transduction. In the working of the eye, absorption of light causes isomerisation of retinal and this induces conformational change in rhodopsin, leading to vision. Previously, our group has shown that conformational change can be used to translate an input (either pH change or ligand binding) into a remote output using dynamic foldamer systems. [1,2] Herein, we describe the development of a rhodopsin-inspired foldamer system where Z to E isomerisation of a dehydroamino acid- based photoswitch leads to reversal of hydrogen bond directionality in an extended ethylene-bridged oligourea foldamer by deleting bifurcated C=O hydrogen bonding interactions. In turn, we hope this will reveal a remote catalytically active thiourea site and switch ‘ON’ the reactivity of a Michael addition reaction involving a nitro olefin and N-methylindole. To achieve a fully ‘OFF’ Z system, several iterations of foldamers were synthesised, enabling conformational fine‑tuning to be informed by variable temperature NMR (VT-NMR) and x-ray crystallography. Studies are currently underway to determine the exact conformation of the thiourea binding site in the active catalyst. This dynamic foldamer system is a prototype for chemical systems capable of photocontrolling reactivity from a distance or through a membrane.
References 1. D. T. J. Morris, S. M. Wales, D. Tilly, E. H. E. Farrar, M. N. Grayson, J. W. Ward and J. P. Clayden, Chem 2021 , 7 , 2460–2472. 2. S. M. Wales, D. T. J. Morris and J. P. Clayden, J. Am. Chem. Soc. 2022 , 144 , 2841–2846.
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© The Author(s), 2023
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